A great series by YT contributor JRwtrains.  The Yakumo service started in March 1972 when the Sanyo Shinkansen came to Okayama.  Until July 1982, KIHA181s in consists as long as 11 cars were used, but with full electrification of the Hakubi Line and this service's portion of the San-in Main Line, the 381s took over.  This was the third region to see the 381 series, having been introduced in 1972 on the Shinano service between Nagoya and Nagano, and in 1978 on the Kuroshio service between Tennoj